In some embodiments, the disclosed subject matter is an assistance system with a wearable assistive device that mitigates the effects of neuro-muscular ailments such as unintended motion, or loss of strength. The assistance system uses predictive analysis based on situational, operational, and historical contexts, when in active/predictive mode. When in reactive mode, the assistive device mitigates unintended motion without altering the strength of the user. The assistance system may have an exercise mode to both assess the user's strength and flexibility of various muscles and joints, and promote exercises to either avoid further losses, or to maintain current strength and flexibility. The assistance system utilizes sensor data from sensors coupled to the assistive device, and optionally from sensors coupled to mobile devices and in the environment. Actuators on the assistive device control movement of the device based on inferred intended actions or reactive to unintended movement.